PSI - Issue 45

7

/ Structural Integrity Procedia 00 (2022) 000 – 000

Quan Jiang et al. / Procedia Structural Integrity 45 (2023) 117–124

123

Fig. 7. The average fiber length, L f , average fiber pull-out length, l p and critical fiber length, L c , of all fiber content and materials.

( ) p V l BW a   (6) The energy dissipated by the fiber withdrawal is regarded as originating from the friction at the interface between the fiber and the matrix phase. Therefore, the total amount of energy dissipated q can be expressed as shown below. cos p f q IFSS l S V   (7) In that equation, φ represents the average orientation angle of the fiber with respect to the loading direction. φ was measured from the X-ray CT observations taken from the surface of the molded product to about 1 mm in the thickness direction. Figure 9 presents an example of the X-ray CT image and the φ measurement image. From them, we obtained the average orientation angle and its distribution. Table 1 shows the φ measurement results. In the Charpy impact test, the Charpy impact strength is obtained by dividing q by the ligament area. Therefore, the final theoretical value a Model is expressed as the following equation (8). Figure 10 portrays the relation between a iN and a Model . The correlation of SGFRTPs presented in this figure is proportional. The coefficient of determination R 2 is almost 0.6, which represents good agreement. In addition, verification results show that the impact strength is explainable by equation (8) when fiber pull-out is the main energy dissipation mechanism. 6. Summary This study investigated the correlation between impact strength and IFSS of injection molded glass fiber-reinforced thermoplastics made of polypropylene and polystyrene matrix. Impact test results indicated fiber pullout as the primary energy dissipation mechanism. A mechanical model with fiber withdrawal as the main energy dissipation mechanism was developed and correlated with the experimentally obtained results. Acknowledgements The X-ray CT images used for this study were taken at the Miyagi Prefectural Industrial Technology Center. This work was supported by JST, the establishment of University fellowships towards the creation of science technology innovation, Grant Number JPMJFS2104. 2 cos IFSS S l  ( BW a  ) Model f p q a   (8)